Strain-induced charge ordering above room temperature in rare-earth manganites

Most known mixed manganites containing rare-earth elements demonstrate a pronounced charge ordering (CO) state below room temperature. The behavior of the magnetic susceptibility and electronic magnetic resonance of polycrystalline Pr_1−xSr_xMnO₃/YSZ (x = 0.2 and x = 0.4) films without a pronounced texture indicates the formation of the CO phase in the samples at temperatures close to and above room temperature. Moreover, this phase manifests itself with a typical sign of martensitic transformation. The same phenomenon has been traced for textured polycrystalline La_0.7Sr_0.3MnO₃/YSZ films. Electron microscope data indicate the presence of internal strain within the films, which is probably responsible for the formation of the CO phase. It is assumed that the reasons for the appearance of such strain include the crystallite size and the boundary between them. The results obtained provide the basis for the development of new research and technological tasks for the generation of the high-temperature CO state in various polycrystalline rare-earth manganites, since this state contributes to the manifestation of interesting magnetocaloric, magnetoelectric and multiferroic properties. In addition, recent data has opened up new opportunities for studying the strain-induced phenomena in such materials.